recipe-7-changing-default-binding-names.adoc

How do I override the default binding names in Spring Cloud Stream?

Problem Statement

Spring Cloud Stream creates default bindings based on the function definition and signature, but how do I override these to more domain friendly names?

Solution

Assume that following is your function signature.

@Bean
public Function<String, String> uppercase(){
...
}

By default, Spring Cloud Stream will create the bindings as below.

1. uppercase-in-0

2. uppercase-out-0

You can override these bindings to something by using the following properties.

spring.cloud.stream.function.bindings.uppercase-in-0=my-transformer-in
spring.cloud.stream.function.bindings.uppercase-out-0=my-transformer-out

After this, all binding properties must be made on the new names, my-transformer-in and my-transformer-out.

Here is another example with Kafka Streams and multiple inputs.

@Bean
public BiFunction<KStream<String, Order>, KTable<String, Account>, KStream<String, EnrichedOrder>> processOrder() {
...
}

By default, Spring Cloud Stream will create three different binding names for this function.

1. processOrder-in-0

2. processOrder-in-1

3. processOrder-out-0

You have to use these binding names each time you want to set some configuration on these bindings. You don’t like that, and you want to use more domain-friendly and readable binding names, for example, something like.

1. orders

2. accounts

3. enrichedOrders

You can easily do that by simply setting these three properties

1. spring.cloud.stream.function.bindings.processOrder-in-0=orders

2. spring.cloud.stream.function.bindings.processOrder-in-1=accounts

3. spring.cloud.stream.function.bindings.processOrder-out-0=enrichedOrders

Once you do that, it overrides the default binding names and any properties that you want to set on them must be on these new binding names.